1. Field of the Invention
The present invention relates to recording ink suitable for recording by an inkjet recording system and a manufacturing method thereof, an ink cartridge, an ink recorded matter, an inkjet recording apparatus, and an inkjet recording method using the recording ink.
2. Description of the Related Art
Recently, an inkjet printer by an inkjet recording system has become popular rapidly, since, for example, the inkjet printer by the inkjet recording system enables printing on plain paper, facilitates colorization, is small and inexpensive, and realizes low running cost. In general, properties required of recording ink used for the inkjet recording system include, for example, an image density, blur and the like to attain a high image quality; solubility stability, storage stability and the like of a coloring agent for attaining reliability; water resistance, light stability and the like to secure storage stability of a recorded image; and quick drying properties of the ink to attain speeding up. Conventionally, various suggestions have been made to satisfy these properties of the recording ink.
As a coloring agent used for the recording ink, dye has been initially a mainstream since the dye has good coloring properties and high reliability. However, recently, pigments such as carbon black have been used for the purpose of providing a recorded image with light stability, water resistance and the like. Further, recently, there is a trend to discharge the recording ink which is broken into small droplets in order to attain a high quality and speeding up of printing. Therefore, a diameter of a nozzle for discharging ink in printers and the like has become smaller. However, it is difficult to stably discharge the recording ink using the pigment by the nozzle with a small diameter. Therefore, many methods of manufacturing recording ink with superior discharge stability have been suggested. For example, a method wherein after recording ink is manufactured, the recording ink is left under unfavorable conditions (for example, for three days at 50° C.) to form agglomeration which is removed by filtration has been suggested (refer to Japanese Patent Application Laid-Open (JP-A) No. 57-190059). In this case, however, there is a problem that manufacturing efficiency of the recording ink is poor, formation properties of the agglomeration vary according to lot-to-lot difference of a raw material, and manufacturing at low cost is not possible.
Therefore, recording ink whose gross volume of particulate matters having a particle diameter of 2 μm or more is from 3.5×10−6 to 1×10−2 (cm3/cm3 ink) has been suggested (refer to Japanese Patent (JP-B) No. 3102209). This suggestion is, however, intended to secure discharge stability by destroying and removing air bubbles generated in an ink flow path, and prevent image defect. In this suggestion, there is a problem that it is not possible to inhibit generation of agglomeration after elapsed time and to sufficiently improve storage stability and discharge stability.
Meanwhile, there is a suggestion that, for the purpose of improving storage stability of recording ink, control is made so that particle quantity of pigment particles having a particle diameter of 0.5 μm or more can become 7.5×104 (quantity/μl ink) or less (refer to JP-A No. 11-140356). In this case, however, a range of pigment density is too low. Therefore, there is a problem that it is difficult to perform high speed printing with high resolution, and refining a high density pigment leads to high cost, which is unrealistic.
Further, for the purpose of improving storage stability and an image density of recording ink, recording ink, whose quantity of particles having a particle diameter of 0.5 μm or more is from 6×104 to 6×105 quantity/μl, and whose quantity of particles having a particle diameter of 5 μm or more is 50 quantity/μl or less has been suggested (refer to JP-A No. 2000-204305). In this case, however, the particles include not only pigment agglomeration, but also water polymer agglomeration, and generation of the pigment agglomeration is not controlled.
In a color image, color boundary bleeding and the like have a significant impact on an image quality. Therefore, in order to raise a rate of permeability of recording ink into paper, and improve quick drying properties of the recording ink, many approaches to secure a high image quality by adding various surfactants and penetrants to the recording ink have been suggested. For example, there is a suggestion that a surfactant whose surface tension is from 20 dyne·cm−1 to 50 dyne·cm−1 at micelle density in water-soluble dye, polyvalent alcohols and water is contained in a recording ink (refer to JP-A No. 55-29546). In this case, apparent drying properties are improved. However, there is a problem that blur becomes significant depending on paper types. Further, there is a suggestion that dialkyl sulfo succinic acid or salt thereof as a surfactant is added to recording ink (refer to Japanese Patent Application Publication (JP-B) No. 60-23793). In this case, however, regarding dioctyl sodium sulfosuccinate, di(2-ethyl hexyl) sodium sulfosuccinate and the like, there is a problem that pixel diameters thereof remarkably vary according to paper types; air bubbles are easily generated when, for example, ink is filled in a cartridge, the cartridge is loaded to a head, the ink is sucked after loading the cartridge, printing is performed, and printing is stopped; and discharge defect is easily caused.
Therefore, there are various suggestions to prevent generation and suck-in of air bubbles. For example, recording ink capable of securing printing stability by improving wet properties to a head and an ink supply system by using ink whose foaming power stability and bubble stability are in a specific range based on JIS K3362-1970, has been suggested (refer to JP-B No. 2707658). In this case, wet properties to a plastic member are improved. However, there is a problem that effects cannot be obtained depending on types of component members of a recording apparatus. Further, recording ink whose bubble stability factor after five minutes is 0 mm (bubble stability factor after one minute is under 5 mm) based on JIS K3362 has been suggested (refer to JP-B No. 07-26049). In this case, however, a material is limited to lower alkyl alcohol having carbon quantity of 5 or less, allowing no versatility. Further, since permeability is low, an image quality in high speed printing is low. Further, recording ink using a specific acetylene glycol surfactant has been suggested (refer to JP-A No. 2000-144026). In this case, however, there is a problem that the specific acetylene glycol surfactant interacts with a coloring agent depending on coloring agent types, and therefore, a drying rate may not be improved. In addition, there is a problem that when a pigment such as carbon black is used, the pigment becomes easy to be agglutinated, and therefore, clogging of a nozzle, turning of ink discharge direction and the like easily arise.
Meanwhile, as a method to improve a drying rate of ink without adding a surfactant, for example, recording ink containing dye and water-soluble glycol ethers has been suggested (refer to JP-A No. 08-113739). Further, an ink composition of matter containing a pigment, glycol ethers such as diethylene glycol mono-n-butyl ether, and water has been suggested (refer to JP-A No. 10-95941). In these cases, however, lots of glycol ethers are to be added in order to improve a drying rate. In result, there are problems that ink gives off a bad smell, safety is not sufficient, and a contact part with the ink becomes deteriorated. Further, carbon black ink containing a specific glycol solvent has been suggested (JP-A No. 07-331142). In this case, however, there is a problem that the carbon black ink containing the specific glycol solvent has insufficient permeability, and an image quality is low. Further, an ink composition of matter containing an organic silicone compound has been suggested (refer to JP-A No. 09-31380). In this case, the ink composition of matter containing the organic silicone compound has defoaming effect. However, the ink composition of matter containing the organic silicone compound has no surfactant and the like, and therefore, there is a problem that its permeability into paper is slow and an image quality is low.
Meanwhile, in order to inhibit foaming properties of ink while securing permeability of ink, there are various suggestions to add a defoaming agent. In general, the defoaming agent has foam inhibiting effect and foam breaking effect. In order to improve the foam inhibiting effect, it is necessary to uniformly disperse the defoaming agent in the ink liquid. Meanwhile, in order to improve foam breaking effect, it is necessary that the defoaming agent exists in the vicinity of a surface of the ink liquid. Therefore, when the defoaming agent is used, it is not easy to actually strike a balance between the foam inhibiting effect and the foam breaking effect. There is a problem that reliability is decreased by insoluble particles added in order to obtain the foam breaking effect.
Therefore, it is a current situation that recording ink, which is suitable for the inkjet recording system, which has superior storage stability, in which discharge stability, particularly discharge stability during continuous discharge or after stopping discharge is improved, and with which a high image quality with little blur can be obtained, and its related art has not been provided yet.
Objects and Advantages
It is an object of the present invention to provide recording ink, which has superior storage stability, in which discharge stability, particularly discharge stability during continuous discharge or after stopping discharge is improved, and with which a high image quality with little blur can be obtained and a manufacturing method thereof, an ink cartridge, an ink recorded matter, an inkjet recording apparatus, and an inkjet recording method using the ink.